Hey Alessandro,
Thanks for reaching out!
Unfortunately, for both of your questions the answer is that yes, could theoretically implement these features but not, they are not features that come with our plugins by default.
So, to limit events to specific user groups, you would have use other plugins to handle the user access, or write custom code.
And for the custom email alerts a day before the event, the same thing is true: you would have to use other plugins to implement this, or write custom code.
In either case, you could also hire someone to build these features for you. Here’s a list of some great customizers we have collected here – we have no affiliation with these folks, this is just a list of well-respected folks in the community: http://m.tri.be/18k1
Cheers!
George